[ELF] Fix LMA offset calculation

[evgeny777]

Summary

Current revision has bug, which causes incorrect LMA offset calculation in section also specifies VMA, i.e:

.foo 0x5000 : AT(0x5000) { *(.bar*) }

This happens because Dot is evaluated after being passed by value to lambda expression

[ruiu]

LGTM

ELF/LinkerScript.cpp

561 ↗

(On Diff #91356)

Please keep the blank line.

lld/trunk/ELF/LinkerScript.cpp

if (Sec->Flags & SHF_ALLOC)
     error("no memory region specified for section '" + Sec->Name + "'");
   return nullptr;
 }
 
 // This function assigns offsets to input sections and an output section
 // for a single sections command (e.g. ".text { *(.text); }").
 template <class ELFT>
 void LinkerScript<ELFT>::assignOffsets(OutputSectionCommand *Cmd) {
-  if (Cmd->LMAExpr) {
-    uintX_t D = Dot;
-    LMAOffset = [=] { return Cmd->LMAExpr() - D; };
-  }
   OutputSection *Sec = findSection<ELFT>(Cmd->Name, *OutputSections);
   if (!Sec)
     return;
 
   if (Cmd->AddrExpr && Sec->Flags & SHF_ALLOC)
     setDot(Cmd->AddrExpr, Cmd->Location);
 
+  if (Cmd->LMAExpr) {
+    uintX_t D = Dot;
+    LMAOffset = [=] { return Cmd->LMAExpr() - D; };
+  }
+
   // Handle align (e.g. ".foo : ALIGN(16) { ... }").
   if (Cmd->AlignExpr)
     Sec->updateAlignment(Cmd->AlignExpr());
 
   // Try and find an appropriate memory region to assign offsets in.
   CurMemRegion = findMemoryRegion(Cmd, Sec);
   if (CurMemRegion)
     Dot = CurMemRegion->Offset;

lld/trunk/test/ELF/linkerscript/at.s

 # RUN:  .ccc : AT(0x3000) \
 # RUN:  { \
 # RUN:   *(.ccc) \
 # RUN:  } \
 # RUN:  .ddd : AT(0x4000) \
 # RUN:  { \
 # RUN:   *(.ddd) \
 # RUN:  } \
+# RUN:  .eee 0x5000 : AT(0x5000) \
+# RUN:  { \
+# RUN:   *(.eee) \
+# RUN:  } \
 # RUN: }" > %t.script
 # RUN: ld.lld %t --script %t.script -o %t2
 # RUN: llvm-readobj -program-headers %t2 | FileCheck %s
 
 # CHECK:      ProgramHeaders [
 # CHECK-NEXT:   ProgramHeader {
 # CHECK-NEXT:     Type: PT_PHDR
 # CHECK-NEXT:     Offset: 0x40

 # CHECK-NEXT:     ]
 # CHECK-NEXT:     Alignment: 4096
 # CHECK-NEXT:   }
 # CHECK-NEXT:   ProgramHeader {
 # CHECK-NEXT:     Type: PT_LOAD
 # CHECK-NEXT:     Offset: 0x1018
 # CHECK-NEXT:     VirtualAddress: 0x1018
 # CHECK-NEXT:     PhysicalAddress: 0x4000
+# CHECK-NEXT:     FileSize: 8
+# CHECK-NEXT:     MemSize: 8
+# CHECK-NEXT:     Flags [
+# CHECK-NEXT:       PF_R
+# CHECK-NEXT:       PF_X
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Alignment: 4096
+# CHECK-NEXT:   }
+# CHECK-NEXT:   ProgramHeader {
+# CHECK-NEXT:     Type: PT_LOAD
+# CHECK-NEXT:     Offset: 0x2000
+# CHECK-NEXT:     VirtualAddress: 0x5000
+# CHECK-NEXT:     PhysicalAddress: 0x5000
 # CHECK-NEXT:     FileSize: 9
 # CHECK-NEXT:     MemSize: 9
 # CHECK-NEXT:     Flags [
 # CHECK-NEXT:       PF_R
 # CHECK-NEXT:       PF_X
 # CHECK-NEXT:     ]
 # CHECK-NEXT:     Alignment: 4096
 # CHECK-NEXT:   }

 .section .bbb, "a"
 .quad 0
 
 .section .ccc, "a"
 .quad 0
 
 .section .ddd, "a"
 .quad 0
+
+.section .eee, "a"
+.quad 0